I recently had a bit of a problem getting one of my zones going. The advice given by Forum members was very quick & helpful in finding a very basic cause for my problem. While waiting for replies I browsed many threads and saw several occurrences of an issue near & dear to my heart; disappointed with my system. I also noticed that several of the pro installers in this forum would get pretty defensive. After a few frustrating years with my system I thought I’d throw in my 2 cents worth. I had my share of disappointments with my system and when I was cold and frustrated I would get pretty negative. Three bloody cold (N Saskatchewan) winters later everything has settled down and here’s where I’m at. I still grumble that my system runs so much but then I remember that the system is designed for -32C and I understand it is expected that the system should run 100% of the time when you get down to design temp. We had a lot sub -30C the past three winters. It’s been suggested to me that this type of heating system is pushing the limits in this climate. Maybe the Pros have something to add here. Another source of frustration is the recovery time. My house is completely insulated with Walltite Eco. At -25C it takes about 45 minutes for the house to drop 1 degree but takes 3+ hours to recover that one degree. Still don’t understand this but since I stay cozy & warm should I care?. Operating cost was another source of annoyance. The prevailing marketing hype will have you believe that your geothermal operating cost will be 25%of conventional heating costs and that’s what I expected at first. I understand that this is a possibility in moderate to mild climates. In our climate, in a 2,000+ sq. Ft. house I’m told that one is very lucky to get in under $4,000 (Cdn) for combined power and heat. My annual costs are averaging about $3,400 so I think I’m doing pretty good; my initial expectations where probably a bit high. Many people have reported a number of equipment failures. After three years of pretty heavy winter running I have not yet experienced any type of failure. My system consists of Climate Master 5 ton TMW & 3 ton TTW. The water-water unit is supported by a 90 gallon buffer tank and supplies 5 zones of in floor heat. Total area heated is 5,000 sq. Ft. (1800 air & 2575 house/625 garage water) The house is a 2150 sq ft bungalow with a full heated walkout basement.I might add that natural gas is not an option in my area. I’ll be interested in what kind of feedback results. One more bone for everyone to chew on; if I was to do it again I wonder if I should choose WaterFurnace?
I'll start with a few thoughts. Your current issue, one could argue was with your radiant system, not with the geothermal. You would have had the same issue with a wood boiler. You can design geo to supply 2x the load in -50c temps, if you needed to. We have to walk the line between economic payback and initial capital costs. Or the opposite, you could design a system for 50% loads that satisfies 80% of runtime. Really just a conversation with the contractor. Your recovery time may be influenced by a few things. Do you use outdoor reset? If not, your house is responding after the temperatures have dropped. Or you could also have a large deadband. Really it shouldnt be 1 degree colder in your house. It should be at temp. If a system does fall behind, it is doing a lot more work to heat a house up at -30c than it would be to maintain temperature. Your payback depends on what fuel you would be comparing to and the local rates.
I cringe to think what it would cost to heat a 5000 SF house with an 8 ton load in North Sask. using propane or fuel oil - surely a LOT more than $3400 metric dollars.
Urthbuoy, It can be argued that the problem mostly lies with the radiant heat system. It is not my intention to argue but have some intelligent conversation that may help me and others get a reasonable handle on what we should expect from our systems. A wood boiler would provide a much higher temperature water and thus produce quite a different result from the radiant heat system. I'm not sure I understand your second statement. I do appreciate drawing a balance between cost and payback. As it is I did opt for a higher initial cost to try and cover that last 20%. I am very interested in your last statement. I'm not sure I understand what you mean by outdoor reset. My system is not tied to any outdoor influences other then it's bloody cold and the house needs heat;-) I have always wondered if my thermostat is working in the most optimal way. I did discuss this with the installer at the beginning and he replaced the thermostat with a different model which yielded some improvement. The way my system works it would appear that there is a one degree differential on the thermostat. Once the house reaches the setpoint the system quits and the thermostat calls for heat again when the temperature drops one degree. Perhaps I should be looking into the possibility that the thermostat can have a narrower differential. It sort of makes sense that if your desire is for 72 degrees the house should pretty much stay at 72 with no really noticeable drop. As for cost, like I said, once I got real I realized my operating costs are not too bad. There are people in this area who are heating similar size houses with natural gas or oil. I am operating cheaper than them but definitely not 25% of their costs. None-the-less I am OK with my costs. If I had natural gas available that probably would have been my first choice. If I was younger and into chopping wood and stoking boilers a good outdoor boiler might have been a better choice. For me, in spite of the $50K cost, geothermal was the best choice. Maybe I can realize even better performance by tweaking the thermostat
Geo doesn't really care about outdoor air temperatures so much as it cares about equipment run times. Your loop is designed on degree days of heating (for your area) based on expected run times. Now you appear to be a predominantly radiant home, based on the size of the heat pumps. Outdoor reset allows you to adjust your buffer tank temperature based on outdoor air temperatures. What is currently controlling the buffer tank temperatures? Manual? Aquastat? Or maybe an outdoor reset. How does your air zone(s) overlap with the radiant zones? Is there interference on the calls? Assuming you can produce all the heat you require, we are just trying to effectively move it around the house. And we may need 50C water to do that when it is -30C out. But we don't need to run the heat pumps that hard when its warmer out. Thus, some sort of outdoor reset control. The 25% is bunk. You are right. Compared to straight electrical heating, yes you'll see those type savings. But other fuel costs, as you've shown, are not as expensive generally.
Urthbuoy, You have piqued my curiosity. I lied a bit, my buffer tank is 120 gal and controlled by an aquastat set to 33. Not sure if I've interpreted overlap correctly. Upstairs is primarily hot air controlled by one thermostat. The majority of the house is open area so the thermostat serves the upstairs fairly well. The bedrooms are isolated from the main area but are fairly comfortable. We prefer a bit cooler in the bedrooms anyways. The entrance way is slate and has radiant heat. The mudroom and laundry are just off the main area and are also slate with radiant heat. Finally the ensuite is also radiant heat. I'm assuming this is what you refer to as overlap. All the upstairs radiant heat is in one zone which is set a degree higher than the air thermostat which is located in the mudroom since that is the most isolated area from the main house.. I'm curious as to what is meant by 'interference on the calls'. Maybe I can benefit from this. Also what is involved with an outdoor re-set? Maybe this too might be of some benefit depending what is involved in implementation at this stage. Thanks.
Outdoor reset is usually provided by a control system. Like a tekmar 406 or eco-0550. It raises the buffertank temperatures as outdoor temps fall.
Andy, Thanks for the info. I'm not going to pretend to understand the system fully but here's my interpretation. It seems to me that my radiant system circulation pumps are circulating the water from the buffer tank and when that water cools down sufficiently the aquastat call for a re-heat from the geothermal pump. Now I'm thinking that the geothermal pump is hard pressed to get the water up to 92 degrees and when it's cold outside that water cools off quicker as the thermostats call for more heat. Now maybe my system is capable of heating the water higher but it seems I've been told that 92 is kinda the max for geothermal heat. I know on the other side that is pretty much the temperature of my duct air. Given that I might be correct in my understanding so far. I'm not sure what an outdoor re-set would do for me. I do see some potential if I had an auxiliary source of heat such as a little electric boiler. The the re-set control could fire up the boiler and raise the temperature in my buffer tank. If that was a practical scenario the Tekmar 406 looks like it does a lot more then that. Appreciate any further clarification and comments. I might have screwed up on this reply so my apologies if it comes across as a double post
Keep in mind im just learning this stuff and am no expert. Your buffer tank is at 92c ? How dose your system do a warm weather shut down? Or dose it keep the buffer tank at 92 year round? The outdoor resets seem to also include a warm weather shut down. This might save some depending on how long you off heating season is. Also in mild weather if you can heat with 80 deg water vs 92 then your gshp should run more efficient. What do the Experts here have to say??
If your heating with 92c water I would think a outdoor reset would greatly help the efficiency. My $0.02
I'm going to say he is talking 92F. Not too many systems that get water close to boiling point. That being said, your geo will happily work in the 80-120F range. So, I would say, 92F is too cool of water to heat your house at the cold temperatures you are getting to. That is when you need outdoor reset to adjust the tank temperature to 110, 115, 120 - whatever. This is where someone experienced with the design of your system typically steps in. Remember, it is measuring outdoor air temperature. So effectively it is heating up the water to a warmer temperature BEFORE you start losing heat in the house. Why a radiant system falls behind is, it is not reacting until you start losing heat and the thermostat drops. You effectively have a lot of thermal "momentum" of heat leaving the house now. So it is hard to catchup. And the varying tank temperatures give you varying btu/ft2 dumped in to your floors. Hotter water equals more btu's/ft2. You may need that increase in thermal output to match your heat loss. And from the sounds of it you do. But then, you also need the system to ramp back down when it is not so cold. Thus outdoor reset. Lots of controls out there to do this with. P.S. My professional opinion is all radiant systems require outdoor reset.
Thanks for the input. yes my 92 degrees is Farenheit (33C). I was told my system could not produce anything much higher than that. It sounds like you are saying different. If I where to crank my aquastat up what kind of additional load is that going to put on the system? If one uses something like the Tekmar 406 is there a sensor that replaces the aquastat. Just for the hell of, what is a Tekmar 406 worth and can it replace my aquastat or are other accessories also required? On this topic of raising the temperature why can I not get more than 92 degrees out of the hot air side. In the super cold weather that 92 degree air is not enough to warm the house. We do manage but at -35 we are hard pressed to get the house above 71 and then the system runs constantly with no shutdowns. To answer one of the other questions, I simply shut down the entire water-water system once the heating system is finished.The other system switches over to air conditioning.
Your air probably can only do 92F. It is a bump of 20F over incoming air temperature - pretty standard. This is assuming your original TTW is a typo and is actually a TTV unit. At this point, I was focused on the hydronic side. If you have air side issues, then look at your deadbands. The temps you're allowing the thermostat to drop to before coming on. Set it to 0.5C or less for your situation. Yes, you can easily connect an outdoor reset to a 406. They come with outdoor reset for that matter. Is that what you want? What zone tstats do you currently have? If you don't already have Tekmar zone stats, the Tekmar 406 may not be a great choice. It wants to work with communicating thermostats. You are paying for features you can't really use. You can just use a boiler control with outdoor reset for the simplest. Or an HBX control as its zone expansions work with non-communicating thermostats. edit - on the air side again. Do you have fresh air ducting connected to the incoming return air? Do you have an HRV unit? Straight fresh air at -30C can take quite a bit of your output away.
re. typo; my water-water unit is a 5ton TMW. My air unit is a Tranquility27(TT). Air side is re-circulating the inside air. HRV refreshes that air once in awhile. I was wondering what a deadband was; take it it's the difference between set point and call for heat. If I narrow that to 0.5C that wont create any hardship from more frequent starts? Back to water, Can you confirm that I can bump my Ranco Aquastat up to 100 -110 without stressing my pump (TMW). Someone referred to the Tek406 but it did look like a pretty elaborate control. I have HoneyWell TH1100DV thermostats for each zone. Is there a simple boiler control that can work together with my aquastat. I don't see how I can eliminate the aquastat. Don't I need something that actually reads the buffer tank temp and call for a warmup? I sure do appreciate all your info. THANKS
Most boiler controls have wired temperature gauges that replace your aquastat. Something like the Tekmar 256 for example. The specs on your equipment show it taking up to 120F entering water temperature. Though I wouldn't want to see you running it that hot. So yes, unless you have seen lockouts (likely from poor load flows) in the past when trying to bump the heat up, your unit is more than capable of dealing with hotter water. Flows are very important. Is the pump large enough to dump all the heat pumps heat in to the buffer tank? Are the radiant pumps able to move btu's to the floors? Etc. For now, I've assumed some smart person somewhere figured this all out and those are taken care of
Chris, Again, thanks for your good info. I looked up the Tek 256 and it looks like it would make a good replacement for my aquastat. As for pumps, I have a Wilo Star 30 moving the water in/out of my buffer tank and a Star 24 feeding my board with 5 StratosECO16s for zone circulaation. As you said, I hope the guy who built my hydronic system knew what he was doing. On the otherhand it was him who maxed my aquastat out at 33 but then he's a heating guy and not a geothermal guy. take care
I recently had a bit of a problem getting one of my zones going. The advice given by Forum members was very quick & helpful in finding a very basic cause for my problem. While waiting for replies I browsed many threads and saw several occurrences of an issue near & dear to my heart; disappointed with my system. I also noticed that several of the pro installers in this forum would get pretty defensive. After a few frustrating years with my system I thought I’d throw in my 2 cents worth. Glad you were helped. We are accused of being defensive from time to timed, I would suggest it is usually when a poster puts blame on the wrong party (i.e. blaming the product when it was actually installer error). There are also tired myths such as "this type of heating system is pushing the limits in this climate" I had my share of disappointments with my system and when I was cold and frustrated I would get pretty negative. Three bloody cold (N Saskatchewan) winters later everything has settled down and here’s where I’m at. I still grumble that my system runs so much but then I remember that the system is designed for -32C and I understand it is expected that the system should run 100% of the time when you get down to design temp. We had a lot sub -30C the past three winters. It’s been suggested to me that this type of heating system is pushing the limits in this climate. Maybe the Pros have something to add here. Again 3 years to sort out the system is an installer bad not an equipment problem. I often tell clients that we are on a journey, monitoring their equipment I often return to tweek our installations. Expectations are also the responsibility of the installer. You should have expected the unit to run 100% of the time even 10-20F north of design temperatures. Multistaged systems are intended to stay in the lowest stage until the equipment loses ground. Your thermostat kicks on stage one after you are one degree below set point and likely stage 2 when you are 2 degrees below. If you regain one degree, many designs will "reverse stage" returning the system to first stage and so forth. If it is cold out it may never get to set point without intervention. Depending on your thermostat you might be happier with .5F differentials. Another source of frustration is the recovery time. My house is completely insulated with Walltite Eco. At -25C it takes about 45 minutes for the house to drop 1 degree but takes 3+ hours to recover that one degree. Still don’t understand this but since I stay cozy & warm should I care?. A variety of things are in play. I recently noticed that in some homes with forced air systems, temperatures drooped as much as 2 degrees when the blower first turned on as stratified air or cold rooms (such as finished basement space with the heat registers closed) was hiding lower actual room temps from the thermostat. This created over active auxiliary and second stage use and also lengthy recovery times. By staying off for 45 minutes I would expect that it would take a while to recover (especially if heated by slab). One of the ways I have improved this is either reduced droop (temp delta between set point and activation) or constant fan where a circulator is involved. Higher temps are less efficient in water to water, but may be necessary sometimes. This could speed recovery, but again bear in mind where my design temp is near 0 degrees F I expect the equipment to run 100% of the time in the high 20's. Operating cost was another source of annoyance. The prevailing marketing hype will have you believe that your geothermal operating cost will be 25%of conventional heating costs and that’s what I expected at first. I understand that this is a possibility in moderate to mild climates. In our climate, in a 2,000+ sq. Ft. house I’m told that one is very lucky to get in under $4,000 (Cdn) for combined power and heat. My annual costs are averaging about $3,400 so I think I’m doing pretty good; my initial expectations where probably a bit high. Again expectation is the salesman's responsibility. I suggest to folks a savings of 60% over LP or fuel oil and we often exceed that. Against Nat Gas right now the savings may not be much more than 10%. Many people have reported a number of equipment failures. After three years of pretty heavy winter running I have not yet experienced any type of failure. My system consists of Climate Master 5 ton TMW & 3 ton TTW. The water-water unit is supported by a 90 gallon buffer tank and supplies 5 zones of in floor heat. Total area heated is 5,000 sq. Ft. (1800 air & 2575 house/625 garage water) The house is a 2150 sq ft bungalow with a full heated walkout basement.I might add that natural gas is not an option in my area. New appliances fail. That's why there are warranties. Go to any furnace forum and you will see complaints of failures. The price of geos does add an emotional element to the victim of a failure, but....if it's made by humans and installed by humans then it can't be perfect. One added element is there is more to designing a good functioning geo system so the opportunity for trouble is greater. The controls for a system such as yours are more complicated and expensive. Later you mentioned what you spent and it was on the low side for a proper geo hydronic system of your magnitude. I’ll be interested in what kind of feedback results. One more bone for everyone to chew on; if I was to do it again I wonder if I should choose WaterFurnace? Let's see you have had trouble with a thermostat, expectations and perhaps design/control but not your heat pumps themselves. What do you imagine would change with a different brand of heat pump? I know one thing that would change; designer/installer. Could be better or could be worse. Tamar is a visitor who had a system that wasn't designed by a particularly un-evolved company and the result was particularly poor. It sounds like your system is about dialed in now. I wish you peace that will come with attainable expectations. Good Luck, j
